Transmitting antenna



Ju y 1929 o. VON BRONK l.72l,174

TRANSMITTING ANTENNA Filed Sept. 3, 1921 SOURCE- OF HIGH SOURCE OF HIGH FREQUENCY ENERGY avwewcoz OTTO von BRONK 351 his 229% I 42 4M Patented July 16, 1929.

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oTTo VON BRONK, 0F BERLIN, GERMANY, ASSIGNOR To GESELLSCHAFT rim DRAHT- LOSE TELEGRAPHIE M. B. H. HALLESGHES, or BERLIN, GERMANY, A coarona- TION OF GERMANY.

. TaANsMITTINe ANTENNA...

Application filsd September a, 1921, Serial No. 498,426, and in Germany August 23, 1917.-

(GRANTED UNDER THE PROVISIONS or THE ACT or MARCH- 3, 1921, 41 STAT. L, 131a An application for this invention was filed in Germany August 23, 1917, Patent No. 313,215.

In a normal antennathe radiation is, according to the theory as accepted today, represented by the relation for the radiation resistance,

where or represents a form-factor, h the height of the capacity above earth and )t the Wave length. As to the correctness of the formula there exist doubts based on practical experience. The wide deviations observed can also be explained as a change of or dependent upon A. But this is certain, that after completed construction of a normal antenna the radiation resistance is still a function of the wave length.

According to the present invention the radiation resistance, within certain limits, can be made independent of the wave length- The drawing Figs. 1 and 2 are diagrammatic representations of two embodiments of the invention. In both cases two antenna-parts are combined into one arrangement. The antenna parts are energized by any convenient and well-known means as by coupling coils supplied by a suitable source of high frequency energy. If both antenna-parts A, and A are equally tuned and if only antenna A, is energized, then a great part of the electric lines of force are closed through the capacity surface of antenna A The ammeter J, in A will therefore show a rather high current. As the entire arrangement is very much closed, the radiation resistance will be a minimum. By making the outer-coupling stronger, for instance, through the magnetic field of the induction coils L, and L the current in A, can be brought down to a minimum. Thereby, of course, the current also decreases in A, as indicated by ammeter J A, then radiates as if A were non-existent. A diminution of the radiation resistance through the antenna-part A can also be obtained by changing the tuning of A relative to A,.

The radiation can be increased above the amount which was reached by the back coupling resulting in zero current in A,, if the antennae A, and A are fed at the same frequency and phase. The maximum is reached when the current in A, and A is approximately equal.

Therefore, the radiation resistance can be constantly changed by this means within the limiting values designated below:

(1) Minimum, when A, and A are operated at the same frequency with 180 phase difference.

(2) Maximum, when A, and A are op erated at the same frequency and in phase.

The arrangement, like any radiator, can also be used as receiver.

It will be evident from the facts pointed out that with the above described change of the radiation resistance, a change in the wave length also takes place. If the Wave length 1s to be maintained constant, then the variable factors defining the wave lengths, self-in ductance or capacity, must be changed correspondingly.

The drawing shows only two antennaeparts. The amount of radiation can, as is at once clear, also be determined through several antennae thus fitted into and onto each other, and changed within limits.

It will be remembered that a closed type of antenna is one in which the radiating circuit is substantially conductively closed on itself. This type of antenna has a relatively low radiating resistance and is inherently a poor radiator. On the other hand, an open type of antenna is one in which the radiating circuit is open to the greatest extent. This type of antenna has a relatively high radiation reslstance and is inherently a good radiator.

It will be easily appreciated that in effect the antenna system according to the present invention is changed from a closed type to an open type simply by changing the energization of the antennae.

When the energization of the antennae is such that the currents are in phase, then the system operates like two open antennae in parallel. On the other hand, when theenergization of the antennae is such that the currents are 180 degrees out of phase, then the system operates like a closed antenna system.

I claim: 1. In an antenna arrangement comprising a plurality of transmitting antennae electrostatically coupled together, the method of I controlling the radiation resistance, comprising the steps 01, impressing voltage on one antenna, and then adjusting the amplitude of a voltage impressed on another antenna so that the current in said antenna has some value between the limits of maximum in phase With the current in said first antenna through zero to maximum 180 degrees out of phase With the current in said first antenna.

2. In an antenna arrangement comprising a plurality of transmitting antennae electrostatically coupled together, the method of controlling the radiation resistance, comprising the steps of impressing voltage on a first antenna, then impressing Voltage on a second antenna to oppose the Voltage induced by electrostatic coupling With said first antenna, and

adjusting said last voltage in amplitude.

In testimony whereof I aflix the signature.

OTTO VON BRONK. 

